1. Field of the Invention
The present invention relates generally to a cooling unit, and more particularly, to a cooling unit to be used with semiconductor elements and other such heat-generating components.
2. Description of the Related Art
Generally, electronic devices are provided with a large number of heat-generating components, first and foremost including the central processing unit, or CPU. As a result, in order to prevent the interior of the device from overheating a cooling unit is provided. In recent years a cooling unit for efficiently driving the CPU has come into particular demand.
Conventionally, the cooling units used in electronic devices are of two types: forced-air types and forced-liquid types. FIG. 1A is a diagram showing a conventional forced-air type cooling unit 100. FIG. 1B is a diagram showing a conventional forced-liquid type cooling unit 200.
As shown in FIG. 1A, the air-cooled cooling unit 100 has a heat sink 103 made from material having a high rate of heat transmission such as aluminum or copper is provided on a heated part 101. The heat sink 103 is provided with a multiplicity of fins in order to increase the radiative effect. In the cooling unit 100 a flow of air forcibly created by a fan 105 cools these fins and so cools the heated part 101.
Additionally, as shown in FIG. 1B, the liquid-cooled cooling unit 200 has thermally conductive cold plates 203 provided in direct contact with the heated part 201. These cold plates 203 are positioned so as to contact a pipe 204 through which a liquid coolant 209 circulates opposite the heated part 201. When the liquid coolant 209 passes through the heat exchanger 207 it is heat exchanged and cooled, so the cold plates 203 can also be cooled and, accordingly, the heated part 201 is also cooled. This liquid-cooled cooling unit 200 has a pump 205 and a heat exchanger 207 having a fan 208 to forcibly cool the heated part 201.
However, the above-described air-cooled cooling unit 100 uses air to cool the heated member 101, so the rate of heat transmission is very low and the radiative effect is poor. Moreover, the above-described cooling unit 100 uses an electrically driven fan 105 and thus requires power, in addition to which the fan generates noise and is subject to breakdowns.
The liquid-cooled cooling unit 200 described above, although it has good thermal conductivity, nevertheless still uses a pump 205 and a fan 208 and so is subject to the same disadvantages as those pertaining to the air-cooled cooling unit 100 described above, namely fan noise and fan breakdowns. Additionally, in the case of the liquid-cooled cooling unit 200 the pump or other equivalent circulatory device requires a great deal of space and must be maintained and serviced as well, which takes time and costs money.
Accordingly, it is a general object of the present invention to provide an improved and useful cooling unit in which the above-described disadvantages are eliminated.
Another and more specific object of the present invention is to provide and improved and useful cooling unit which does not use an external power source and hence is quiet, economical, efficient and capable of effectively cooling heated parts.
The above-described objects of the present invention are achieved by a cooling unit comprising:
a heat receiving unit that receives heat from a body radiating heat;
a radiator unit disposed at a distance from the heat receiving unit and radiating recovered heat;
a liquid coolant transporting heat generated at the heat receiving unit to the radiator; and
a hollow tube disposed so that the liquid coolant circulates between the heat receiving unit and the radiator,
a circulating flow of the liquid coolant formed by an elevating force of air bubbles generated from the heat received at the heat receiving unit, the radiator having an air pocket forming one part of the circulation path of the liquid coolant together with the hollow tube and capable of collecting the air bubbles.
According to the invention described above, the circulation path of the liquid coolant is formed by the motive force created by the elevating force of the air bubbles, so the liquid coolant can be circulated without the use of an external drive source, thus making it possible to transfer the heat of the heat-receiving part to the radiator via the liquid coolant at reduced cost and no noise. Additionally, the heat of the heat-receiving part is absorbed as the heat of evaporation when the liquid coolant is turned into a gas and the heat of aggregation is released when the air bubbles that reach the radiator are condensed and returned to a liquid state, so heat can be transferred more efficiently from the heat receiving part to the radiator and a cooling unit of high cooling effectiveness and efficiency can be provided.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.